Source size and time dependence of multifragmentation induced by (GeVHe)-He-3 beams - art. no. 014603

To investigate the source size and time dependence of multifragmentation re actions, small- and large-angle relative velocity correlations between coin cident complex fragments have been measured for the 1.8-4.8 GeV He-3+ Ag-na t, Au-197 systems. The results support an evolutionary scenario for the fra gment emission process in which lighter IMFs (Z less than or similar to 6) are emitted from a hot, more dense source Frier to breakup of an expanded r esidue. For the most highly excited residues, for which there is a signific ant yield of fragments with very soft energy spectra (E/A less than or equa l to 3 MeV), comparisons with an N-body simulation suggest a breakup time o f tau similar to 50 fm/c for the expanded residue. Comparison of these data with both the evolutionary expanding emitting source model and the Copenha gen statistical multifragmentation model shows good agreement for heavier I MF's formed in the final breakup stage, but only the evolutionary model is successful in accounting for the lighter IMFs. [S0556-2813(99)01707-0].